Thin film surgical dressing with delivery system

ABSTRACT

A pressure sensitive adhesive composite with a delivery system having particular benefit in application of very thin backings such as high moisture vapor permeable films widely used as medical dressings is disclosed. The composite has a backing coated with adhesive on at least a portion of the backing and liner over the adhesive. At least one edge of the backing is a delivery strip which is separable from the remainder of the backing. The liner is securely adhered to the delivery strip and releaseably adhered to the remainder of the adhesive coated backing. The bond between the a liner and the delivery strip is strong enough that the delivery strip will separate from the remainder of the backing before it will separate from the liner.

FIELD OF INVENTION

The present invention relates to pressure sensitive adhesive (PSA)composites comprising a backing coated on at least one side withadhesive. More particularly it relates to a PSA composite having adelivery system to aid placing the composite on a surface. The inventionis of particular benefit in applications of very thin films such as thehigh moisture vapor permeable films widely used as medical dressings.

BACKGROUND

Although the present invention is useful in any adhesive compositeneeding a delivery system, it has particular benefit in connection withtransparent film dressings and surgical drapes. These dressings anddrapes are widely used as a protective layer over a wound, facilitatinghealing in a moist environment while acting as a barrier to liquids andbacteria. Dressings of this type are available under trade names such asTegaderm™ (3M, St. Paul, MN) Bioclosure™ (Johnson & Johnson, NewBrunswick, N.J.) and Op-Site™ T. J. Smith & Nephew, Hull, England).Uniflex™ (Howmedica, Largo, Fla.), U.S. Pat. No. 3,645,835, which ishereby incorporated by reference, describes one such moisture vaporpermeable, water bacteria impermeable dressing.

The polymeric films used in such dressings are extremely thin, flimsy,and supple. They are supplied with a releasable protective lineroverlying the adhesive coated surface of the film. When the liner isremoved the adhesive coated film tends to fold and stick to itselfforming wrinkles which render smooth aseptic application of a dressingor drape to skin very difficult. Various delivery systems have beenproposed to obviate this problem.

One such delivery system utilizes a frame to support the edges of thefilm during its application. European Pat. Appln. No. 81 30 4905describe a composite having a relatively thin polymeric film which isconformable to animal anatomic surfaces. A pressure sensitive adhesiveis coated to at least a portion of one surface of the polymeric film. Arelease liner is attached to the adhesive coated surface of the film. Asecond releasable layer or carrier is attached to the opposing (exposed)surface of the film. This second releasable layer is attached to thefilm more tenaciously than the release liner is adhered to the adhesiveside of the film and is preferably a frame adhered to the periphery ofthe film. In use the releasable layer stays with the film until the filmis affixed to the substrate, at which time it may be removed.

Another delivery system is utilized in the Op-Site™ dressing. In thatdressing the film is provided with a pull tab along one edge of thefilm. The releasable liner is removed by peeling the liner and the pulltab away from each other. The pictorial instructions supplied with theproduct suggest that the dressing should be applied by grasping the pulltab and the releasable liner which has been partially removed and thenplacing the film on the intended site. Thereafter the releasable lineris completely peeled off and the dressing smoothed to the skin surface.The pull tab can be left in place or, in an alternative embodiment, thepull tab and the film to which it is adhered are removed from theremainder of the dressing by separation along perforations provided forthis purpose. U.S. Pat. No. 4,413,621 describes such a dressing.

A third delivery system is described in European Pat. Appln. No. 84 300752.7 (publication No. 0,120,570). That application describes a wounddressing made of a film that is coated on one face with a biocompatibleadhesive. One or more liner sheets are releasably adhered to theadhesive coated surface. Release retarding means are provided along oneedge or a pair of opposed edges of the dressing to require a greaterforce to separate the layers (film, adhesive, and liner) at the edge oredges than at the remainder of the contact area. The release retardingmeans may be a thicker strip of the polymeric film, a stiffer piece offilm adhered to the film at its edges, a strip of liner backing wrappedaround the edge of the film and adhered to the surface of the film, or astrip attached to the exposed surfaces of both the film and the backing.Alternatively an adhesive having greater tenacity than the quick releaseadhesion of the biocompatible adhesive for the liner may be used.

SUMMARY OF THE INVENTION

The adhesive composite of the present invention has three layers--abacking, a pressure sensitive adhesive layer coated on at least aportion of one surface of the backing, and a liner over the adhesive. Atleast one edge of the backing is a delivery strip which is separablefrom the remainder of the backing. The liner is securely adhered to thedelivery strip portion of the adhesive-coated backing and it isreleasably adhered to the remaining surface of the adhesive-coatedbacking. The bond between the liner and the delivery strip is strongenough that the delivery strip will separate from the remainder of thebacking before it will separate from the liner.

The backing is preferably a film provided with perforations to definethe delivery strip edge. In use pulling firmly on the liner which isadhered to the delivery strip of the film but which has been peeled backfrom the remaining areas of the film will cause the film to tear alongthe perforations.

The preferred adhesive coated film is permeable to moisture and vaporand should transmit moisture vapor at a rate of at least 300 g/m² /24Hrs/37° C./100-10% RH. Preferably the adhesive coated film transmitsmoisture vapor at a rate of at least 700 g/m² /24 Hrs/37° C./100-10% RH.When a high moisture vapor permeable film is used the adhesive ispreferably biocompatible. Most preferably the PSA composite compriseshigh moisture vapor permeable film, a biocompatible adhesive and istransparent.

The preferred method of securely attaching the liner to the deliverystrip entails use of a conventional liner material which has been stripcoated with a releasing agent, e.g. silicone. In the preferredembodiment the liner is left free of any releasing agent along the stripthat contacts the delivery strip of the film. The remaining surfaces ofthe liner, that is those areas that will releasably contact the PSAcoated film, are coated with the releasing agent. In a composite of thistype, the adhesion of the liner to the pressure sensitive adhesivecoated on the delivery strip may be increased by irradiation. Adhesiveswhich increase their adhesion upon irradiation are known in the art.When the adhesive is a copolymer of iso-octylacrylate and acrylamideirradiation to increase adhesion can take place simultaneously withsterilization when gamma irradiation is used.

The adhesive composite of the present invention may be constructed withtwo delivery strips at opposing edges of the film. In this embodimentthe liner is comprised of at least first and second segments wherein thefirst segment is adhered to one delivery strip and the second segment isadhered to the opposing delivery strip. Preferably in this embodimentthe two segments of the liner are releasably adhered to the adhesivecoated film and meet near the center of the film. They are preferablyprovided with an extension of liner material to facilitate peeling ofthe liner segments. These extensions may be integral with the liner orseparate pull handles adhered to the liner. They may be folded in aconventional "J" fold. Alternatively one piece of liner can be folded ina "J" fold while the continuing surface of the second piece of linerextends beyond the "J" fold of the first.

In an alternative embodiment the film has one delivery strip at one edgeand the liner extends across the entire adhesive-coated surface of thefilm. In this embodiment the film is preferably provided with a pull tabat the edge opposing the delivery strip edge of the film. In use thepull tab may be left in place after application of the film, or the pulltab may be releasably adhered to the film and removed after applicationof the film. In this latter alternative the pull tab should adhere tothe film with greater tenacity than the adhesion of the releasableportions of the liner.

In the method of this invention a thin flexible adhesive coated film isapplied to a substrate wherein the film has a delivery strip along atleast one edge thereof which strip is a separable from the remainder ofthe film and a liner is adhered to the adhesive coated surface of thefilm which liner is adhered to the delivery strip of the film withsufficient tenacity to result in separation of the delivery strip fromthe remainder of the film before the liner-delivery strip bond fails andwhich liner is releasably adhered to the skin contacting surface of thefilm. The composite is applied by removing the liner from the substratecontacting surface of the film, placing the substrate contacting surfaceof the film into intimate contact with the intended site, and thereafterseparating the liner and delivery strip from the film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of the adhesive composite of thepresent invention;

FIG. 2 is a perspective view of the adhesive composite of the presentinvention;

FIG. 3 is a plan view of the adhesive composite of the present inventionshowing the liner surface;

FIG. 4 is a cross section of view of the present invention showingseparation of the releasable portions of the liner from an adhesivecoated film;

FIG. 5 is a cross section view of the present invention showingapplication of an adhesive coated film to a substrate.

FIG. 6 is a perspective view of an alternative embodiment adhesivecomposite showing a composite with a unitary liner and a pull tab on thefilm.

DETAILED DESCRIPTION

The delivery system of the present invention is useful in connectionwith any backing having a pressure sensitive adhesive coated on to it.Representative backings include nonwoven fibrous webs, fibrous filmwebs, knits, and other familiar backing materials. The preferred backingmaterials are polymeric films. The invention is particularly useful inPSA composites having high moisture vapor permeable films. U.S. Pat. No.3,645,835 describes a method of making such a high vapor/moisturepermeable film and a method for testing its permeability.

The film is also preferably conformable to body surfaces. Generally thefilms are from 12 to 25 microns thick. Conformability is somewhatdependent on thickness, thus the thinner the film the more conformableit is. In the preferred embodiment the films used in the device of thepresent invention are conformable to animal anatomical surfaces. Thismeans that when the film is applied to an animal anatomical surface itconforms to the surface even when the surface is moved. The preferredfilms are conformable to animal anatomical joints. When the joint isflexed and then returned to its unflexed position, the film stretches toaccommodate the flexion of the joint but is resilient enough to continueto conform to the joint when the joint is returned to its unflexedcondition. A measure of conformability is the F₁₀ modulus. The F₁₀modulus should be no greater than about 1 pound (454 grams) andpreferably less than about 0.8 pounds (363 grams). In the preferredembodiments of wound dressings and drapes, films which have F₁₀ moduliupwards of 2.5 pounds (1135 grams) may be used. However, as the F₁₀modulus increases the conformability decreases and the ability of thefilm to perform comfortably as medical dressings likewise decreases.

F₁₀ modulus as referred to herein is effectively determined using anInstron Unit Model 1102 from Instron Corp., 2500 Washington Street,Canton, Mass. The cross-head speed of the Instron is set at ten inchesper minute and the chart speed is set at ten inches (25.4 cm) perminute. The gauge length is set at two inches (5 cm) with the testsample cut to test a one-inch width (2.54 cm).

Examples of polymers which are suitable for use as wound dressing filmsin the present invention include polyurethane, elastomeric polyestersuch as DuPont "Hytrel" polyester elastomer (Wilmington, Delaware),polyethylene, blends of polyurethane and polyester, chlorinatedpolyethylene, styrene/butadiene block copolymers such as "Kraton" brandthermoplastic rubber (Shell Chemical Company, Houston Tex.), andpolyvinyl chloride.

Particularly preferred films are polyurethane and elastomeric polyesterfilms. These films combine the desirable properties of resiliency, highmoisture vapor permeability and transparency.

The preferred adhesives which can be used in the preferred wounddressing embodiment are the normal adhesives which are applied to theskin such as those described in U.S. Pat. No. Re. 24,906, particularly acopolymer of 96% iso-octyl acrylate units and 4% acrylamide units and acopolymer of 94% iso-octyl acrylate units and 6% acrylic acid units.Other useful adhesives are those described in U.S. Pat. No. 3,389,827which comprise block copolymers having three or more polymer blockstructures having a general configuration --A--B--A-- wherein each A isa thermoplastic polymer block with a glass transition temperature aboveroom temperature (i.e., above about 20° C.) having an average molecularweight between about 5000 and 125,000 and B is a polymer block of aconjugated diene having an average molecular weight between about 15,000and 250,000. Additional examples of useful adhesive are iso-octylacrylate/n-vinyl pyrrolidone copolymer adhesives and crosslinkedacrylate adhesives such as for example those described in U.S. Pat. No.4,112,213. Inclusion in the adhesive of medicaments or antimicrobialagents such as iodine is useful for enhancing wound healing andpreventing infection. U.S. Pat. Nos. 4,310,509 and 4,323,557 describeantimicrobial adhesives.

The liner is preferably strip coated with a releasing agent applied tothe liner only in the areas which will contact the substrate (e.g. theskin contacting surface of the film). No release agent is applied to thestrips which will contact the delivery strips of the film. Examples ofliners suitable for use in the present invention are strip coated linersmade of kraft papers, polyethylene, polypropylene or polyester, and arecoated with releasing agents such as fluorochemicals or silicone. U.S.Pat. No. 4,472,480 describes low surface energy perfluorochemicalliners. The preferred liners are silicone coated release papers,polyolefin films, or polyester films. Examples of the silicone coatedrelease papers are Polyslik™ silicone release papers supplied by H. P.Smith Co., Chicago, Ill. and silicone coated papers supplied by DaubertChemical Co., Dixon, Ill. The preferred liner is75-W-89-SPT3A-Zoned/PST3A paper available from Schoeller ReleaseProducts, West Chicago, Ill. This products is a polyethylene coatedkraft paper bearing an electron beam cured silicone surface. Thesilicone is coated in the areas which are releasably adhered to thesubstrate (e.g., skin) contacting surface of the film and uncoated inthe areas which are adhered to the delivery strips of the film.

Other combinations of adhesive and liner are feasible. Those skilled inthe art are familiar with process of testing a new adhesive againstdifferent liners, or a new liner against different adhesives in order toarrive at the combination of qualities desired in the final product.Handbook of Pressure-Sensitive Adhesive Technology, Chapter 18 "SiliconeRelease Coatings"Van Nostrand-Reinhold, 1982, pp. 384-403, which ishereby incorporated by reference describes the considerations pertinentto selection of a silicone release liner. U.S. Pat. No. 4,472,480 whichis hereby incorporated by reference describes considerations pertinentto selection of a perfluoropolyether liner. In the preferred wounddressing embodiment of the present invention, the choice of adhesive islimited to those that are safe to use on skin, and preferably to thosethat are of the class known as hypollergenic. The preferredpolyacrylates are adhesives of this class. Liners are available from avariety of manufacturers in a wide variety of proprietary formulations.One normally tests these in simulated use conditions against an adhesiveof choice to arrive at a product with the desired releasecharacteristics.

In the present invention, a parameter in addition to selection of theadhesive, the liner, and the method of fixation can be varied to achievethe desired tenacity of adhesion of the liner to the delivery strip.This factor is the perforations or line of weakness put into the film toallow breakage of the delivery strip from the remainder of the film. Forexample, after the combination of adhesive and liner which give thedesired low peel force when removing the liner is selected a pattern ofperforations is developed, which is found to hold when the film isgently held taut while being applied, but which breaks when a slightlygreater pull is applied by the user. Too few perforations will result ina film which stretches, deforms, and tears unevenly. Too many or toolarge perforations will yield a film which tears to readily.

FIG. 1 shows the preferred embodiment of the present invention. Thisembodiment is a wound dressing 10 shown as received by the user. Forclarity, protective and sterile outer wrappings are not shown. Thedressing is made of a thin transparent, polymeric film 11 which ismoisture vapor permeable, liquid and bacteria impermeable such as apolyester or polyurethane film. A coating of biocompatible pressuresensitive adhesive 20 such as non-allergenic polyacrylate bioadhesivecovers the lower, skin contacting surface of the film. A liner in twosegments 31 and 32 covers the adhesive. The two segments meet near thecenter of the dressing and are provided with integral extensions 33 and34 which serve as handles to be grasped by the user when removing theliner segments. One extension 33 is virtually flat; the other extension34 is shown folded in a "J" pattern. At the two opposed edges of thefilm 11 are delivery strips 12 and 13. The delivery strips 12 and 13 aredefined by the edges of the film and the perforation lines 14 and 15.The liner segments 31 and 32 are firmly adhered to the adhesive coateddelivery strips 12 and 13. This affixing may be accomplished in severalways. The fixation may be mechanical. A heat sea may be used. Anotherway is to have the liner strip coated with a release agent (e.g.silicone). As best shown in FIG. 3, therefore liner 31 is coated withrelease agent in the portion defined by lines 35 and 36. The remainingportion of the liner (defined by lines 35 and 37) is left free ofrelease agent. The portion which has no release agent is firmly adheredto the delivery strip 12, preferably by increasing the strength ofadhesion between the adhesive coated delivery strip 12 and the liner byirradiation. In the preferred embodiment where the adhesive is acopolymer of iso-octylacrylate and acrylamide, the bond between thedelivery strip and the liner may be conveniently increased duringsterilization of the product with gamma irradiation. The bond formedbetween the liner and the delivery strip is stronger than the line ofweakness (e.g. perforations 14 and 15 best shown in FIG. 2) whichpermits separation of the delivery strip from the skin contactingsurface of the film.

FIG. 4 shows the dressing of FIG. 1 being prepared for application to awound. For ease of illustration the dressing has been folded around lineA--A shown in FIGS. 2 and 3. With the film 11 being extremely flexibleand bent as shown in FIG. 4, and where the liner is chosen so as to havelow adhesion of the liner to the film, liner segment 31 begins to peeloff the adhesive coated film. When a gentle pull is applied to linersegment 31 as indicated by arrow 40, this peeling will continue untilthe entire segment 31 is peeled from the film except for the portiondefined by lines 35 and 37 which is securely adhered to the deliverystrip 12. With continued gentle pulling of the liner 31 the film willunfold and the other segment of the liner 32 will peel off the filmuntil the condition shown in FIG. 5 is reached. Alternatively, the linersegments 31 and 32 may be peeled from the adhesive coated filmsimultaneously. When this procedure is employed the condition shown inFIG. 5 is similarly reached.

FIG. 5 shows the dressing 10 with the adhesive coated surface positionedfor application the wound. Further increasing the tension applied to theskin 50 of a patient over a wound 51. The dressing is made taut bygentle tension applied in directions 41 and 42. It is then smoothed downonto the wound. Further increasing the tension applied to the film bypulling the liner segments will cause the film to break alongperforation lines 14 and 15. After the film tears along the perforations14 and 15 the film lies flat on the skin and, because of its physicalcharacteristics, forms a homogeneous and unobtrusive dressing whichconforms well to the contours of the skin. The liner and delivery stripsare discarded.

FIG. 6 shows an alternative embodiment of the present invention. Thisembodiment, shown as a wound dressing 100, has a liner 300 formed as onesegment. The dressing is made of a thin transparent, polymeric film 110which is moisture vapor permeable and liquid and bacteria impermeable. Acoating of biocompatible pressure sensitive adhesive 200 such aspolyacrylate bioadhesive covers the lower skin contacting surface of thefilm. A liner 300 covers the adhesive. At one edge of the film is adelivery strip 120. The delivery strip is defined by the edge of thefilm and perforation line 140. At the opposite end of the film 110 is apull tab 170. The pull tab 170 may be an extension of the film having noadhesive and without perforations, or it may have a perforation line 171so that it can be removed after application of the dressing to the skin.The liner is firmly adhered to the delivery strip. The remainingportions of the liner is releasably adhered to the remainder of thefilm. To apply this dressing the user grasps the pull tab 170 and beginsto peel the liner 300. Then holding the pull tab and liner thereleasable portion of the liner is removed and the film is placed ontothe intended site and smoothed. At this time a firm tug will cause thedelivery strip to separate from the remainder of the film.

The composite of the present invention may be made by conventionaltechniques (e.g. extrusion, solvent casting, calendering, and laminatingand the like) which are familiar to those skilled in the art. (SeeModern Plastics Encyclopedia McGraw Hill, 1984-85; Coating andLaminating Machines, Weiss Converting Technology Co., 1977.) The methodof making a composite is further exemplified by the following nonlimiting example.

EXAMPLE

Twenty five grams per square meter of an adhesive prepared in accordancewith U.S. Pat. No. Re. 24,906, which is incorporated by reference,comprising of copolymer of 96% units of isooctylacrylate and 4% unitsacrylamide was applied to a release liner of 78 pounds (35412 grams)bleached, one-side coated, polyethylene and silicone paper (PolyslikS-8053, H. P. Smith, Chicago, Ill. utilizing a standard horizontal knifecoater. A 1.1 mil (28 micron) film of "Estane 58309NAT022 polyurethaneresin (B. F. Goodrich, Cleveland, Ohio) was laminated to the adhesivesurface. This material was then slit to proper width to make the sizedressing desired. The adhesive/film laminate was then removed from theS-8053 release liner and relaminated to the J folded and flat finishedproduct release liner (75W-89SPT3A-Zoned/PST3A, Schoeller ReleaseProducts, West Chicago, Ill.) to form a roll of double liner bandagestock with non-silicone strip or each edge of roll. The perforating andslitting of the dressing to size were performed using adie-cutting/printing machine (Model 813, Series KZY223, Mark Andy, St.Louis, Mo.).

The foregoing description has been directed to particular preferredembodiments for purposes of illustration and explanation. Those skilledin the art will appreciate that many modifications will be possiblewithout departing from the spirit of the invention. For example thecomposite may further comprise a gauze dressing or the pressuresensitive adhesive may be pattern coated to increase moisture vaportransmission rate and decrease pain upon removal of a dressing. Thefollowing claims are intended to be interpreted to embrace all suchmodifications and variations.

What is claimed is:
 1. An adhesive composite comprising a backingwherein at least one edge of the backing is a delivery strip which isseparable by perforations from the remainder of the backing;a pressuresensitive adhesive coated on at least a portion of one surface of thebacking; and a liner which is adhered to the delivery strip withsufficient tenacity to result in separation along the perforations ofthe delivery strip from the remainder of the backing before the linerseparates from the delivery strip and which liner is releasably adheredto the remainder of the backing.Iadd., wherein the liner is strip coatedwith releasing agent such that the portion contacting the delivery stripis free of releasing agent and the portion contacting the remainder ofthe film has releasing agent. .Iaddend.
 2. The composite of claim 1wherein the backing is a polymeric film.
 3. The adhesive composite ofclaim 2 wherein the adhesive coated film has moisture/vapor transmissionrate of at least 300 g/m² /24 hrs/37° C./100-10% RH and the adhesive isbiocompatible.
 4. The adhesive composite of claim 3 wherein the film istransparent. .[.5. The adhesive composite of claim 2 wherein the lineris strip coated with releasing agent such that the portion contactingthe delivery strip is free of releasing agent and the portion contactingthe remainder of the film has releasing agent..].
 6. The adhesivecomposite of claim .[.5.]. .Iadd.1 .Iaddend.wherein the releasing agentis silicone.
 7. The adhesive composite of claim .[.5.]. .Iadd.1.Iaddend.wherein the adhesion of the pressure sensitive adhesive coatedon the delivery strip to the liner is increased by irradiation.
 8. Theadhesive composite of claim 7 wherein the pressure sensitive adhesive isa copolymer of iso-octylacrylate and acrylamide.
 9. The adhesivecomposite of claim 2 wherein the film has two delivery strips atopposing edges of the film and the liner is comprised of at least afirst segment and a second segment wherein the first segment is adheredto one delivery strip and the second segment is adhered to the opposingdelivery strip.
 10. The adhesive composite of claim 2 wherein the filmhas a delivery strip at one edge and pull tab at the opposing edge. .The adhesive composite of claim 10 wherein the pull tab is releasablyadhered to the film with greater tenacity than the adhesion ofreleasable portions of the liner.
 12. A method of applying a thinflexible adhesive coated film to a substrate wherein the film has adelivery strip along at least one edge thereof which is separable fromthe remainder of the film and a liner adhered to the adhesive-coatedsurface of the film which liner is adhered to the delivery strip portionof the film with sufficient tenacity to result in separation of thedelivery strip from the remainder of the film before the liner-deliverystrip bond fails and which is releasably adhered to the remainder of thefilm.Iadd., wherein the liner is strip coated with releasing agent suchthat the portion contacting the delivery strip is free of releasingagent and the portion contacting the remainder of the film has releasingagent, .Iaddend.comprising:removing the liner from the substratecontacting surface of film; placing the substrate contacting surface inintimate contact with the skin; and separating the liner and deliverystrip from the film.